Polishing systems for use with semiconductor substrates including differential pressure application apparatus

ABSTRACT

An apparatus for applying different amounts of pressure to different locations of a backside of a semiconductor device structure during polishing thereof. The apparatus is configured to be associated with a wafer carrier of a polishing apparatus and includes pressurization structures configured to be biased against the backside of the semiconductor device structure during polishing thereof. The pressurization structures are independently movable with respect to one another. The amount of force or pressure applied by each pressurization structure to the backside of the semiconductor device structure is controlled by at least one corresponding actuator. The actuator may magnetically facilitate movement of the corresponding pressurization structure toward or away from the backside of the semiconductor device structure. The actuator may alternatively comprise a positive or negative pressure source. Systems including the pressure application apparatus, as well as differential pressure application methods and polishing methods are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of application Ser. No. 09/912,982,filed Jul. 25, 2001, pending.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to apparatus that apply pressureto the backsides of semiconductor device structures during polishing orplanarization of one or more layers thereof. Particularly, the presentinvention relates to apparatus that selectively apply different amountsof pressure to different locations on the backsides of semiconductordevice structures as one or more layers on the opposite, active surfacesthereof are polished or planarized. More particularly, the presentinvention relates to apparatus that employ magnetic fields toindependently apply pressure to different, selected locations on thebackside of a semiconductor device structure. The present invention alsorelates to polishing methods wherein different amounts of pressure areselectively applied to different locations on the backside of asemiconductor device structure, as well as to systems for effecting suchmethods.

2. Background of Related Art

Chemical-mechanical polishing and chemical-mechanical planarization areabrasive techniques that typically include the use of a combination ofchemical and mechanical agents to planarize, or otherwise removematerial from, a surface of a semiconductor material substrate bearingdevices under fabrication. Such a structure may be referred to for thesake of convenience as a “semiconductor device structure.” A chemicalcomponent, typically a slurry that includes one or more oxidizers,abrasives, complexing agents, and inhibitors, oxidizes the surface ofone or more material layers that are being polished or planarized (i.e.,at least partially removed). A polishing pad, or CMP pad, is used withthe slurry and, along with abrasives present in the slurry, effectsmechanical removal of the layer or layers from the surface of thesemiconductor device structure. It should be noted that abrasive-onlypolishing and planarization, e.g., without the use of active chemicalagents to effect material removal, are becoming more prevalent due toenvironmental concerns. Thus, the term “CMP” as used herein encompassessuch abrasive-only methods and apparatus.

Conventional CMP pads are round and planar and have larger dimensionsthan the semiconductor substrates (e.g., wafers or other substratesincluding silicon, gallium arsenide, indium phosphide, etc.) upon whichthe structures or layers to be polished have been formed. In polishingone or more layers of structures formed on a substrate, the substrateand the conventional CMP pad are rotated relative to one another, withthe location of the substrate being moved continuously relative to thepolishing surface of the pad so that different areas of the pad are usedto polish one or more of the layers or structures formed on thesubstrate.

When conventional polishing processes are used, the surface of asemiconductor device structure following polishing thereof is often notplanar. Due to the rotation of at least the semiconductor devicestructure during polishing, the periphery of the semiconductor devicestructure moves at a faster rate than the center thereof. Thus, materialis removed from the periphery of a rotated semiconductor devicestructure more quickly than material is removed from more centralregions of the semiconductor device structure.

In addition, although the inhibitors of a slurry function to even outthe polishing rate across nonplanar surfaces, polishing of structureswith initially great differences in height may not result in a planarsurface, but may result in a surface with raised “rings”.

As exemplified by U.S. Pat. No. 6,050,882 to Chen (hereinafter “Chen”),attempts have been made to increase the planarity to which semiconductordevice structures are polished. Chen discloses a wafer carrier headapparatus that includes independently movable rods. Rods that arelocated outside of the periphery of a semiconductor device structureassembled with the carrier head extend at least partially downward tolaterally confine the semiconductor device structure during polishing ofone or more layers thereof. Rods that contact the backside of thesemiconductor device structure are biased against all locations of thebackside with equal amounts of pressure or force provided by positiveair pressure applied to a single pressurizable bladder located above allof the rods. Chen also discloses another embodiment of the carrier head,wherein a pressurizable chamber may be located centrally relative to therods so as to apply pressure to the central region of a semiconductordevice structure assembled with the carrier head or to act as a vacuumchuck when a negative pressure is applied to the chamber. The chambermay be used to apply a different amount of pressure to the backside ofthe semiconductor device structure than that applied to the peripheralregions of the backside of the semiconductor device structure by therods. Nonetheless, the carrier heads of Chen do not facilitate theapplication of different amounts of pressure to different, selectedlocations on the backside of a semiconductor device structure inresponse to preventing nonplanarities at specific locations on theactive surface of the semiconductor device structure. Moreover, as thecarrier heads of Chen are configured to apply only one or two differentamounts of pressure to a semiconductor device structure during polishingthereof, these carrier heads will not adequately compensate fornonplanarities that may be formed during polishing but, rather, mayaccentuate these nonplanarities.

Accordingly, it appears that the art lacks apparatus for applyingselected amounts of pressure to one or more different, selectedlocations on the backsides of semiconductor device structures duringpolishing thereof, as well as methods for selectively applying pressureto selected locations on the backside of a semiconductor devicestructure during polishing thereof.

SUMMARY OF THE INVENTION

The present invention includes polishing methods and apparatus withwhich substantially planar surfaces may be formed on semiconductordevice structures during polishing thereof.

In one aspect of the present invention, a surface of a polishedsemiconductor device structure is analyzed to identify one or morelocations thereon where material was removed at a slower rate thanremaining locations on the surface. Areas on the surface of thesemiconductor device structure where material is removed at decreasedrates will typically be higher than, or raised above, other areas on thesurface. By increasing the amount of friction between the surface of thesemiconductor device structure and a polishing pad at these raisedareas, the rate of material removal may be increased. In the presentinvention, the friction at these raised areas is increased by applyingforce to the backside of the semiconductor device structure, oppositeeach raised area on the active surface thereof. The amount of force tobe applied to the backside, opposite each raised area, depends upon theheight of the raised area relative to the lowest area on the surface ofthe semiconductor device structure. Thus, the amount of force that isapplied to one location or to different locations on the backside of thesemiconductor device structure may be determined based on the differencein height between each raised area and the lowest area or areas on theactive surface of the semiconductor device structure and by determiningthe amount of friction needed at each of these areas to provide asubstantially constant material removal rate across the entire surfaceof the semiconductor device structure and to form a substantially planarsurface on the semiconductor device structure during polishing thereof.

The present invention includes a differential pressure applicationapparatus that selectively applies different amounts of pressure todifferent locations on the backside of a semiconductor device structure,such as a wafer, upon which a plurality of semiconductor devices isbeing fabricated. The differential pressure application apparatusincludes a plurality of independently movable pressurization structuresthat are configured to be biased against different locations on thebackside of a semiconductor device structure. A controller, or actuator,corresponds to each of the pressurization structures and is configuredto bias the corresponding pressurization structure against the backsideof the semiconductor device structure with a selected amount of force orpressure, the latter being defined as the force-per-unit area.

The controllers are preferably magnets. Thus, each controller may beformed from a magnetic material or comprise an electromagnet. Thepressurization structures, which may be formed from either a magneticmaterial or a material that is attracted to a magnetic field, each movein response to relative movement of the corresponding magneticcontroller.

For example, if the pressurization structures are formed from a magneticmaterial, the controllers may be located and oriented so as to bias thecorresponding pressurization structures against the backside of asemiconductor device structure by repulsion. Of course, like magneticpoles of a controller and its corresponding pressurization structuremust face one another for the magnetic controller to repel thecorresponding magnetic pressurization structure. The amount ofrepulsion, or the amount of force with which the pressurizationstructure is biased against the backside of the semiconductor devicestructure, depends upon the magnetic field strengths of the controllerand its corresponding pressurization structure, as well as upon theamount of movement desired or closeness of the controller to itscorresponding pressurization structure.

Alternatively, a magnetic controller may be located and oriented so asto attract a corresponding magnetic pressurization structure toward thebackside of a semiconductor device structure. Of course, such attractionis effected by positioning a magnetic controller and its correspondingmagnetic pressurization structure so that opposite magnetic poles of thecontroller and pressurization structure face one another. As the desireddirection of movement for the pressurization structures is toward thesemiconductor device structure, when magnetic attraction is used to biasthe pressurization structures against the backside of a semiconductordevice structure, the magnetic controllers are positioned on the side ofthe semiconductor device structure opposite from the magneticpressurization structures.

Alternatively, the pressurization structures may be configured so thatthey are biased against the backside of a semiconductor device structurewhen substantially no magnetic field is applied to the pressurizationstructures. For example, the pressurization structures may beresiliently biased (e.g., by springs) against the backside of asemiconductor device structure. When sufficient magnetic fields areapplied to these resiliently biased pressurization structures, thepressurization structures begin to be moved away from the backside ofthe semiconductor device structure. Thus, the amount of force with whicheach pressurization structure is biased against the backside of aparticular location of a semiconductor device structure may beselectively reduced, or such force may be substantially completelyremoved. In such a configuration of the differential pressureapplication apparatus, the pressurization structures may be formed fromeither a magnetic material or a material that is attracted to a magneticfield. Of course, the relative locations and orientations of thepressurization structures and their corresponding controllers dependupon the type of material from which the pressurization structures aremade, as well as whether magnetic repulsion or attraction is used tobias each pressurization structure against the backside of asemiconductor device structure with a selected amount of force.

As the selective application of different amounts of pressure to thebackside of a semiconductor device structure is particularly useful inpolishing one or more layers of the semiconductor device structure so asto form a substantially planar surface thereon, the pressurizationstructures of the present invention may be incorporated into a wafercarrier of a polishing apparatus. A semiconductor device structure, suchas a wafer with distinct semiconductor devices being fabricated thereon,may be secured to the wafer carrier as known in the art, such as by useof a clamping structure that physically secures at least a portion ofthe periphery of the semiconductor device structure or a vacuum appliedto the backside of the semiconductor device structure through spacesbetween adjacent pressurization structures.

Depending upon the manner in which the pressurization structures are tobe biased by their corresponding controllers against the backside of thesemiconductor device structure, the controllers may also be associatedwith the wafer carrier, or may be located on a side of a polishing padopposite from the wafer carrier, with corresponding pressurizationstructures and controllers being kept in constant alignment. If thecontrollers are located on a side of a polishing pad opposite from theircorresponding pressurization structures, lateral movement of thecontrollers relative to the polishing pad substantially mirrors lateralmovement of the pressurization structures contained within the wafercarrier.

Methods and systems for planarizing semiconductor device structures thatincorporate teachings of the present invention are also within the scopeof the present invention.

Other features and advantages of the present invention will becomeapparent to those of skill in the art through a consideration of theensuing description, the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the drawings, which illustrate exemplary embodiments of theinvention:

FIG. 1 is a cross-sectional representation of a first embodiment of anapparatus embodying teachings of the present invention, illustrating asemiconductor device structure assembled therewith and secured thereto;

FIGS. 1A and 1B schematically depict a variation of the pressureapplication apparatus shown in FIG. 1, wherein solenoids are used inplace of the electromagnets of the apparatus shown in FIG. 1;

FIG. 2 is a bottom plan view of the apparatus illustrated in FIG. 1;

FIG. 3 is a cross-sectional representation of a second embodiment of anapparatus according to the present invention;

FIG. 4 is a cross-sectional representation of a third embodiment of anapparatus of the present invention;

FIG. 5 is a cross-sectional representation of a fourth embodiment of anapparatus incorporating teachings of the present invention;

FIG. 6 is a cross-sectional representation of a fifth embodiment of anapparatus incorporating teachings of the present invention;

FIG. 7 is a cross-sectional representation of a sixth embodiment ofpressure application apparatus of the present invention;

FIG. 8 is a cross-sectional representation of a seventh embodiment ofpressure application apparatus of the present invention;

FIGS. 9A and 9B are schematic cross-sectional representations of aneighth embodiment of pressure application apparatus incorporating theteachings of the present invention, including pressurization structuresthat vary in thickness depending upon an amount of electric or magneticfield applied thereto; and

FIG. 10 is a schematic representation of a system that includes theapparatus of the invention and that effects the substantially planarpolishing of semiconductor device structures in response tononplanarities that are formed on a semiconductor device structure oflike type when an apparatus of the invention is not used.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIGS. 1 and 2, a wafer carrier 1 including anexemplary pressure application apparatus 10 that incorporates teachingsof the present invention is illustrated. As shown in FIG. 1, pressureapplication apparatus 10 is located within wafer carrier 1 within areceptacle 2 for receiving at least a backside 24 portion of asemiconductor device structure 20.

Various types of semiconductor device structures 20 may be assembledwith and secured to wafer carrier 1, including, without limitation, fullor partial wafers of silicon or other semiconductive materials (e.g.,gallium arsenide or indium phosphide), as well as other large-scalesubstrates (e.g., a silicon-on-insulator (SOI) substrate, such assilicon-on-glass (SOG), silicon-on-ceramic (SOC), silicon-on-sapphire(SOS), or the like).

Pressure application apparatus 10 includes a plurality of independently,substantially vertically movable pressurization structures 12, each ofwhich are configured to be biased against the backside 24 of asemiconductor device structure 20 assembled with wafer carrier 1.Preferably, pressurization structures 12 apply pressure to backside 24in a direction that is perpendicular to a plane of semiconductor devicestructure 20 so as to prevent rutting on an active surface 22 ofsemiconductor device structure 20, which may occur if a pressurizationstructure 12 tilts. Pressure application apparatus 10 also includes aplurality of actuators 14, which are preferably magnetic controllers,each of which corresponds to a pressurization structure 12. Knownprocesses, such as the application of a negative pressure to backside 24of semiconductor device structure 20, may be used to securesemiconductor device structure 20 within a receptacle 2 of wafer carrier1 during polishing.

As nonplanarities that arise from polishing are typically in the form ofraised rings, each pressurization structure 12 may be configured as aring, as shown in FIG. 2, so as to apply an appropriate amount of forceto an annular-shaped region of backside 24 of a semiconductor devicestructure 20 assembled with wafer carrier 1 to achieve a desiredpressure on backside 24 throughout a corresponding annular regionthereof. This pressure counteracts the tendency of annular-shapednonplanarities to form on corresponding annular regions of the opposite,polished active surface 22 of semiconductor device structure 20. Theportions of pressurization structures 12 that are biased againstbackside 24 of semiconductor device structure 20 may be substantiallyflat so as to reduce or eliminate the application of localized force onbackside 24, which could cause semiconductor device structure 20 tofracture or otherwise damage semiconductor device structure 20.Pressurization structures 12 may also be relatively tall structures soas to prevent binding between adjacent pressurization structures 12 orbetween a pressurization structure 12 and a corresponding sleeve 16.

In the embodiment of pressure application apparatus 10 illustrated inFIGS. 1 and 2, each pressurization structure 12 comprises a magnet withthe north pole N being located at the top thereof. The magneticstrengths of pressurization structures 12 are preferably substantiallythe same. Each pressurization structure is preferably oriented so as tobe repelled by a corresponding magnetic actuator 14 aligned therewithand configured similarly thereto.

Apparatus 10 may also include a membrane 17 disposed across receptacle 2so as to separate pressurization structures 12 from backside 24 ofsemiconductor device structure 20. Membrane 17, which is preferablyformed from a tough, flexible material that permits the transmission offorce from pressurization structures 12 to backside 24, may protectbackside 24 and, when pressurization structures are lubricated, preventlubricant from contacting semiconductor device structure 20. By way ofexample and not to limit the scope of the present invention, polymericfilms may be used as membrane 17.

As depicted in FIG. 1, actuators 14 are substantially stationaryelements, such as electromagnets, that are configured to emanatediffering strengths of magnetic fields. The electromagnets of actuators14 are oriented such that the north poles N thereof face, or are closestto, the north poles of the corresponding pressurization structures 12.Of course, south poles of pressurization structures 12 and the magneticfields of the electromagnets of their corresponding actuators 14 mayalternatively face one another. When electromagnets are used, thestrengths of magnetic fields emanating therefrom depend upon the amountof electrical current applied thereto, which may be varied, as known inthe art. Actuators 14 are oriented so that the magnetic fields emanatingtherefrom will repel the corresponding pressurization structure 12 uponthe generation of a magnetic field of at least a threshold strength. Thedifferent strengths of magnetic fields that are applied by an actuator14 to its corresponding pressurization structure 12 determines theamount of force with which the pressurization structure 12 is biasedagainst backside 24 of semiconductor device structure 20. Thus, eachactuator 14 of pressure application apparatus 10 is configured toselectively maintain its corresponding pressurization structure 12 outof contact with, or apply substantially no force to, backside 24 ofsemiconductor device structure 20 or to cause its associatedpressurization structure 12 to be biased against backside 24 with aplurality of different amounts of force, or pressure.

Pressure application apparatus 10 may also include a plurality ofindependent springs 13, each of which is associated with a correspondingpressurization structure 12. Each spring 13 may be a known type ofspring that is suitable for maintaining a position of a correspondingpressurization structure 12 relative to a backside 24 of a semiconductordevice structure 20 when a corresponding actuator 14 is not acting uponpressurization structure 12. For example, and not to limit the scope ofthe present invention, spring 13 may be a conventional mechanical,coiled spring, a leaf spring, a Belleville spring, an elastomericspring, a pneumatic (air) spring, or combinations thereof. In the caseof pressure application apparatus 10, each spring 13 is configured andpositioned to maintain its corresponding pressurization structure 12 insuch a position that substantially no force is applied to backside 24 ofsemiconductor device structure 20 unless the corresponding actuator 14causes pressurization structure 12 to be biased against backside 24.Each spring 13 thus pulls its corresponding pressurization structure 12away from backside 24 of semiconductor device structure 20 in theabsence of a magnetic field emanating from the corresponding actuator14.

Alternatively, pressurization structures 12 may be attracted towardtheir corresponding actuators 14 to facilitate the application ofdifferent amounts of pressure to different locations on backside 24 ofsemiconductor device structure 20 during polishing of active surface 22thereof. If pressurization structures 12 are formed from a magneticmaterial, opposite magnetic poles of pressurization structures 12 andthe magnetic fields generated by the electromagnets of theircorresponding actuators 14 face each other to facilitate such magneticattraction. As an alternative, pressurization structures 12 may beformed from a material, such as a ferrous material, that is attracted tothe magnetic field generated by the electromagnets of theircorresponding actuators 14. In addition, when actuators 14 of pressureapplication apparatus 10 attract their corresponding pressurizationstructures 12, springs 13 may be oriented so as to push theircorresponding pressurization structures 12 toward backside 24 ofsemiconductor device structure 20 when a magnetic field is not beingapplied to that pressurization structure 12. Preferably, when magneticfields are not being applied to pressurization structures 12, theamounts of pressure applied by springs 13 and their correspondingpressurization structures 12 to backside 24 are substantially the sameas one another, so that there is a uniform, constant pressure appliedacross backside 24 of semiconductor device structure 20.

As shown in FIG. 1, each pressurization structure 12 and itscorresponding actuator 14 may be substantially isolated from adjacentpressurization structures 12 and actuators 14 by way of an annularsleeve 16 of a material responsive to magnetic fields and preferably aferrous, nonmagnetic material. Thus, sleeve 16 may prevent magneticinterference between an actuator 14 and a noncorrespondingpressurization structure 12. Sleeve 16 may also act as a bearingstructure to prevent lateral movement of pressurization structure 12,substantially confining the movement of pressurization structure 12 to adirection that is substantially perpendicular to the plane of asemiconductor device structure 20 to be assembled with wafer carrier 1.Sleeves 16 may also be coated with a known lubricating material, such assilicone oil, to facilitate movement of pressurization structures 12within their corresponding sleeves 16. Alternatively, adjacentpressurization structures 12 may prevent one another from movinglaterally and, thereby, substantially confine the movement of eachpressurization structure 12 to a direction that is substantiallyperpendicular to a plane of a semiconductor device structure 20 to beassembled with wafer carrier 1.

FIGS. 1A and 1B illustrate a variation of the pressurization structureand its associated actuators of a pressure application apparatus 10incorporating teachings of the present invention. As illustrated,pressurization structure 12 is annular in shape and includes a number ofrods 215 protruding upwardly therefrom. Preferably, rods 215 are formedfrom iron or another ferrous material. Actuators 214 comprise solenoids,each of which includes an electromagnetic coil 216 that is operablyconnected to a power source 217. A corresponding rod 215 that protrudesfrom pressurization structure 12 extends through electromagnetic coil216 of an actuator 214. Upon application of power to electromagneticcoil 216 of the solenoid of each actuator 214, a magnetic field isgenerated which forces rod 215 downwardly, in turn pushingpressurization structure 12 downward so as to apply pressure to abackside 24 of a semiconductor device structure 20 assembled with awafer carrier 1, such as those shown in FIG. 1. Of course, otherpressure application apparatus incorporating teachings of the presentinvention may likewise include multiple actuators associated with asingle pressurization structure.

An alternative embodiment of pressure application apparatus 10′ is shownin FIG. 3. Each of the features of pressure application apparatus 10′are substantially the same as those of pressure application apparatus 10shown in FIGS. 1 and 2, with the exception that actuators 14′ comprisemagnets that each emanate a magnetic field of fixed strength and areconfigured to be moved toward and away from their correspondingpressurization structure 12, as indicated by the arrows. Preferably,each actuator 14′ has associated therewith a mechanical component, suchas a pneumatically or hydraulically driven piston, that effects themovement thereof toward and away from the corresponding pressurizationstructure 12. Actuators 14′ are oriented so as to repel theircorresponding pressurization structures 12 and, therefore, to biaspressurization structures 12 against backside 24 of a semiconductordevice structure 20 assembled with wafer carrier 1′. As a magneticactuator 14′ is moved toward its corresponding magnetic pressurizationstructure 12, the amount of repulsion between pressurization structure12 and actuator 14′ increases. Conversely, as a magnetic actuator 14′ ismoved away from its corresponding pressurization structure 12, the forceof repulsion between pressurization structure 12 and actuator 14′decreases. Thus, the amount of force, or pressure, with which apressurization structure 12 is biased against backside 24 of asemiconductor device structure 20 assembled with wafer carrier 1′depends upon the distance between an actuator 14′ and its correspondingpressurization structure 12.

As in the embodiment illustrated in FIGS. 1 and 2 and described withreference thereto, pressure application apparatus 10′ shown in FIG. 3may alternatively include actuators 14′ that are oriented so as tomagnetically attract their corresponding pressurization structures 12.Of course, the springs of such a pressure application apparatus 10′would be oriented so as to return pressurization structures 12 to anonbiased state relative to backside 24 of semiconductor devicestructure 20 upon reducing or releasing the attractive magnetic fieldthat biases pressurization structures 12 against backside 24.

Another embodiment of pressure application apparatus 10″ incorporatingteachings of the present invention is depicted in FIG. 4. Whilepressurization structures 12″ are contained within a wafer carrier 1″within a receptacle 2″ thereof, their corresponding actuators 14″ arepositioned in a separate actuation component 18″, which is located on aside of a polishing pad 3″ opposite from wafer carrier 1″. Asillustrated in FIG. 4, each actuator 14″ of actuation component 18″ isan electromagnet that corresponds to one pressurization structure 12″.Actuators 14″ are oriented so that at least their correspondingpressurization structures 12″ are attracted toward actuators 14″ uponapplication of current to actuators 14″ to generate a magnetic field(i.e., opposite magnetic poles of pressurization structures 12″ andtheir corresponding actuators 14″ face one another). As actuators 14″are separated from their corresponding pressurization structures 12″ bya semiconductor device structure 20 and a polishing pad 3″ during use,the current that is applied to selected actuators 14″ preferablygenerates a sufficiently large magnetic force field through polishingpad 3″ and semiconductor device structure 20 to attract and bias thecorresponding pressurization structures 12″, as desired, againstbackside 24 of semiconductor device structure 20. The amounts of forcethat are applied by pressurization structures 12″ to various locationsof backside 24 prevent the formation of nonplanarities on active surface22 of semiconductor device structure 20 during polishing of one or morelayers thereof. Again, the amount of current applied to eachelectromagnet actuator 14″ depends upon the desired amount of force tobe applied by pressurization structures 12″ against selected locationsof backside 24 of semiconductor device structure 20.

Referring now to FIG. 5, another exemplary embodiment of a pressureapplication apparatus 10′″ according to the present invention isillustrated. Pressure application apparatus 10′″ includes a wafercarrier 1′″, such as that depicted in FIG. 4. Pressure applicationapparatus 10′″ also includes an actuation component 18′″ locatedadjacent a polishing pad 3′″, on a side thereof opposite from wafercarrier 1′″. Actuation component 18′″ includes actuators 14′″ that arealigned with and correspond to pressurization structures 12′″ of wafercarrier 1′″. Each actuator 14′″, which may be moved vertically towardand away from its one or more corresponding pressurization structures12′″, is formed from a magnetic material. If pressurization structures12′″ are formed from a material that is attracted toward a magneticfield, such as a ferrous material, the amount of force eachpressurization structure 12′″ applies against backside 24 of asemiconductor device structure 20 assembled with wafer carrier 1′″increases the closer the corresponding actuator 14′″ is moved towardpolishing pad 3′″ and wafer carrier 1′″. Likewise, pressurizationstructures 12′″ may be formed from a known magnetic material andoriented so that opposite magnetic poles of each pressurizationstructure 12′″ and its corresponding actuator 14′″ are positionedclosest to one another, or face one another. Again, upon moving anactuator 14′″ toward one or more corresponding pressurization structures12′″, the increased magnetic forces acting on the one or morepressurization structures 12′″ increase the amount of force applied bythe one or more pressurization structures 12′″ to backside 24 of asemiconductor device structure 20 assembled with wafer carrier 1′″.

An alternative embodiment of a pressure application apparatus 110incorporating teachings of the present invention is illustrated in FIG.6. Pressure application apparatus 110 includes a wafer carrier 101positioned on one side of a polishing pad 103 and an actuation component118 positioned on the other side of polishing pad 103, opposite fromwafer carrier 101.

Wafer carrier 101 includes a receptacle 102 formed therein andconfigured to receive a semiconductor device structure 20. Wafer carrier101 also includes a plurality of pressurization structures 112, eachformed from a magnetic material, located within receptacle 102. Eachpressurization structure 112 moves substantially perpendicularly to aplane of a semiconductor device structure 20 disposed in receptacle 102and, thus, assembled with wafer carrier 101. Pressurization structures112 move independently from one another so as to facilitate theapplication of different amounts of pressures to different locations onbackside 24 of semiconductor device structure 20. Each pressurizationstructure 112 includes an associated spring 113, such as a mechanical,coiled spring, a leaf spring, a Belleville spring, an elastomericspring, a pneumatic (air) spring, or a combination thereof, positionedso as to cause the corresponding pressurization structure 112 to bebiased against backside 24 of semiconductor device structure 20.

With continued reference to FIG. 6, actuation component 118 includesactuators 114 that correspond to pressurization structures 112 of wafercarrier 101. Each actuator 114 is independently movable toward and awayfrom polishing pad 103, as well as the pressurization structure 112 thatcorresponds to actuator 114. Each actuator 114 is a magnet oriented soas to repel each corresponding pressurization structure 112 upon beingmoved toward that corresponding pressurization structure 112. Thus, likemagnetic poles of pressurization structures 112 and their correspondingactuators 114 are positioned most closely to one another, or face oneanother. Upon movement of an actuator 114 toward polishing pad 103 and,thus, toward one or more corresponding pressurization structures 112,the one or more pressurization structures 112 are repelled, reducing theamount of force applied by the one or more pressurization structures 112against backside 24 of semiconductor device structure 20 under bias of aspring 113. Once an actuator 114 is moved away from polishing pad 103and, thus, away from one or more corresponding pressurization structures112, spring 113 again relaxes to bias the one or more pressurizationstructures 112 against backside 24.

Still another embodiment of pressure application apparatus 110′incorporating teachings of the present invention is illustrated in FIG.7. Pressure application apparatus 110′ includes a wafer carrier 101′that includes a receptacle 102′ and pressurization structures 112′.Receptacle 102′ is configured to receive and retain a semiconductordevice structure 20. Pressurization structures 112′ may be annular inshape and are positioned so as to be biased against a backside 24 of asemiconductor device structure 20 assembled with wafer carrier 101′.Each pressurization structure 112′ has associated therewith at least onespring 113′ oriented so as to bias pressurization structure 112′ againstbackside 24. Adjacent pressurization structures 112′ are isolated fromone another by way of sleeves 116′. In addition, each pressurizationstructure 112′ has associated therewith a vacuum source 130. Vacuumsource 130 may comprise separate vacuum sources for each pressurizationstructure 112′. Alternatively, vacuum source 130 may comprise a singlevacuum source selectively connected to each pressurization structure112′ through a manifold. To vary the magnitude of vacuum or negativepressure applied, throttling valves may be employed between vacuumsource 130 and each pressurization structure 112′. The amounts ofnegative pressure that may be applied to each pressurization structure112′ is, of course, independent from the amounts of negative pressurethat may be applied to the other pressurization structures 112′. As anegative pressure is applied by vacuum source 130 to a pressurizationstructure 112′, pressurization structure 112′ is drawn away frombackside 24 of a semiconductor device structure 20 within the confinesof sleeve 116′, thus reducing the amount of force or pressure applied bypressurization structure 112′ to the corresponding locations of backside24. As each pressurization structure 112′ may be independently moved inthis manner, different amounts of pressure may be applied to orwithdrawn from backside 24.

Another, similar embodiment of pressure application apparatus 110″ isillustrated in FIG. 8. While pressure application apparatus 110″includes a wafer carrier 101″ with a receptacle 102″ and sleeves 116″that separate and confine adjacent pressurization structures 112″ fromone another, springs 113″ are configured to maintain their correspondingpressurization structures 112″ in a position away from a backside 24 ofa semiconductor device structure 20 assembled with wafer carrier 101″. Apositive pressure source 140 is associated with each pressurizationstructure 112″. Different amounts of positive pressure may be applied bypositive pressure source 140 to a piston 117 adjacent eachpressurization structure 112″. As positive pressure source 140 appliespositive pressure to a head 117 a of piston 117, the correspondingpressurization structure 112″ is moved by piston 117 against theresistance of the corresponding spring 113″, which is coiled around arod 117 b of piston 117, and that pressurization structure 112″ isbiased against backside 24 of semiconductor device structure 20 with adesired amount of force or pressure. As such movement of eachpressurization structure 112″ is independent from that of the otherpressurization structures 112″, different amounts of pressure may beapplied to backside 24 at different locations thereof to generate aforce gradient to be applied across backside 24 of semiconductor devicestructure 20.

Yet another embodiment of pressure application apparatus 110′″ is shownin FIGS. 9A and 9B. Pressure application apparatus 110′″ includes awafer carrier 101′″ with a receptacle 102′″ formed therein andconfigured to receive at least a backside 24 of a semiconductor devicestructure 20. Pressure application apparatus 110′″ also includes, withinreceptacle 102′″, a plurality of pressurization structures 112′″.Pressurization structures 112′″ each include multiple layers 112 a′″,112 b′″, 112 c′″, etc. of a material with a thickness dimension thatchanges upon varying a voltage or a magnetic field applied thereto.Exemplary materials include so-called piezoelectric, magnetostrictive,and electrostrictive materials. Known piezoelectric materials include,but are not limited to, poled polycrystalline ceramic materials, such asbarium titanate and lead zercanate titanate. When piezoelectric orelectrostrictive materials are used as pressurization structures 112′″,a voltage may be applied, in parallel, to each of layers 112 a′″, 112b′″, 112 c′″, etc. to change the thickness of each pressurizationstructure 112′″. Adjacent layers 112 a′″, 112 b′″, 112 c′″, etc. may beelectrically isolated from one another. Preferably, the tops 111′″ ofpressurization structures 112′″ are in a fixed position such that thebottoms 115′″ of pressurization structures 112′″ may exert pressure onbackside 24 of semiconductor device structure 20 assembled with wafercarrier 101′″. Upon disposing semiconductor device structure 20 withinreceptacle 102′″, bottoms 115′″ of pressurization structures 112′″preferably contact backside 24. Upon applying a voltage to eachpressurization structure 112′″, the overall thickness of pressurizationstructure 112′″ increases, causing bottom 115′″ of that pressurizationstructure 112′″ to be forced against backside 24 of semiconductor devicestructure 20 and, thereby, to apply a desired amount of pressure to anappropriate location of backside 24 of semiconductor device structure20. Alternatively, magnetic fields of varying strength may beselectively applied to pressurization structures 112′″ formed from knownmagnetostrictive materials to selectively vary the thicknesses ofpressurization structures 112′″. Preferably, if magnetostrictivematerials are used as pressurization structures 112′″, the magneticfields that are used to vary the thicknesses of adjacent pressurizationstructures 112′″ are substantially isolated from one another by way ofsleeves 116′″.

FIG. 10 schematically illustrates a polishing system 200 that includes apolishing apparatus 210 with a pressure application apparatus 10,including a wafer carrier 1, and a polishing pad 3. Polishing apparatus210 of polishing system 200 may comprise any known type of polishingapparatus, such as a conventionally configured polishing apparatus witha rotating pad, a web-format polishing apparatus, or a belt-formatpolishing apparatus. Although the reference numeral 10 is used herein toidentify a pressure application apparatus, any embodiment of pressureapplication apparatus incorporating teachings of the present inventionmay be used in polishing system 200. If polishing system 200 includes awafer carrier 1 that precesses (i.e., undergoes compound rotation aroundmore than one axis) or includes pressurization structures 12 that arenot annular in shape and wafer carrier 1 is separate from actuationcomponent 18 and positioned on a side of a polishing pad 3 oppositetherefrom, then actuation component 18 is preferably moved laterallyrelative to polishing pad 3 in a fashion that substantially mirrors, ortracks, the lateral movement of wafer carrier 1 relative to polishingpad 3 (e.g., during precessing), thus maintaining the alignment ofpressurization structures 12 and their corresponding actuators 14, aswell as the amount of force applied by each pressurization structure 12(FIG. 1) against backside 24 of a semiconductor device structure 20assembled with wafer carrier 1 during polishing of active surface 22 ofsemiconductor device structure 20.

In using a pressure application apparatus incorporating teachings of thepresent invention while polishing a semiconductor device structure 20,semiconductor device structure 20 is assembled with and secured to awafer carrier, such as wafer carrier 1 shown in FIG. 1. The wafercarrier may then be moved toward a polishing pad 3, such thatsemiconductor device structure 20 is brought into contact with thepolishing pad. Desired amounts of pressure are applied to differentlocations on backside 24 of semiconductor device structure 20 bypressurization structures, such as pressurization structures 12 shown inFIG. 1, under control of corresponding actuators, such as actuators 14shown in FIG. 1. Preferably, pressure is not applied to backside 24 ofsemiconductor device structure 20 until active surface 22 ofsemiconductor device structure 20 is disposed against and supported bythe polishing pad, thereby preventing the occurrence of fractures orcracks that could otherwise be caused in semiconductor device structure20 if pressure were applied to backside 24 thereof prior to disposingactive surface 22 thereof against the polishing pad. The wafer carrieris then rotated so as to effect polishing of active surface 22 ofsemiconductor device structure 20. Preferably, the pressure applied todifferent locations of backside 24 of semiconductor device structure 20causes areas on active surface 22 that would otherwise be raised to bepolished at an increased rate, thereby creating a substantially planaractive surface 22.

Polishing system 200 may also include a metrology component 212 and aprocessor 213 associated with polishing apparatus 210. Metrologycomponent 212, which is of a type known in the art, is configured toanalyze a topography of an active surface 22 of a semiconductor devicestructure 20. This analysis of the topography of active surface 22 ofsemiconductor device structure 20 is communicated from metrologycomponent 212 to processor 213 by way of one or more signals embodied incarrier waves. Processor 213, under control of one or more programs,determines an amount of pressure to be applied at selected locations ofbackside 24 of semiconductor device structure 20 to counteract andreduce nonplanarities formed on active surface 22 during polishing of acertain type of material at a certain rotational speed and for a certainduration. Such a force gradient may be relatively consistent forsemiconductor device structures 20 of the same type.

As an example of the use of polishing system 200, a first semiconductordevice structure 20 a of a group of semiconductor device structures 20is polished by polishing apparatus 210 using conventional processes.Following polishing of active surface 22 of first semiconductor devicestructure 20 a, the topography of active surface 22 is analyzed bymetrology component 212. Data representative of the analysis of activesurface 22 by metrology component 212 is communicated to processor 213,which also considers other facts, such as data regarding the rate atwhich material was removed from a lowermost region of active surface 22to identify an amount of pressure to be applied to selected portions ofbackside 24 of at least one subsequently polished semiconductor devicestructure 20 b of the same type as semiconductor device structure 20 aso as to reduce or eliminate the occurrence of nonplanarities on activesurface 22 of semiconductor device structure 20 b. Processor 213communicates with actuation component 18 so as to control the movementof actuators 14 or the strength of the magnetic field generated byactuators 14, in turn controlling the amount of force with which eachpressurization structure 12 of wafer carrier 1 is biased againstbackside 24 of semiconductor device structure 20 b. Processor 213 andpressure application apparatus 10 thereby generate a force, or pressure,gradient to be applied to backside 24 of semiconductor device structure20. Of course, data representative of the topography of active surface22 of semiconductor device structure 20 may be used in manualcalculations to determine the amount of force to apply to selectedlocations of backside 24 of semiconductor device structure 20 b.Actuation component 18 may similarly be manually controlled so as toapply desired amounts of pressure to different locations of backside 24of semiconductor device structure 20 b.

Although the foregoing description contains many specifics, these shouldnot be construed as limiting the scope of the present invention, butmerely as providing illustrations of some of the presently preferredembodiments. Similarly, other embodiments of the invention may bedevised which do not depart from the spirit or scope of the presentinvention. Features from different embodiments may be employed incombination. The scope of the invention is, therefore, indicated andlimited only by the appended claims and their legal equivalents, ratherthan by the foregoing description. All additions, deletions andmodifications to the invention as disclosed herein which fall within themeaning and scope of the claims are to be embraced thereby.

1. A system for polishing a semiconductor device structure, comprising:a metrology component for detecting any raised areas on an activesurface of the semiconductor device structure; a support structureconfigured to receive the semiconductor device structure; apressurization component including: a plurality of independently movablepressurization structures; and actuators corresponding to each of theplurality of pressurization structures, the actuators each beingconfigured to bias a corresponding pressurization structure against abackside of the semiconductor device structure with a selected amount offorce; and a polishing component.
 2. The system of claim 1, wherein eachof the plurality of pressurization structures comprises a magnetizedmaterial.
 3. The system of claim 1, wherein each of the plurality ofpressurization structures comprises a material that is attracted to amagnetic field.
 4. The system of claim 3, wherein each of the pluralityof pressurization structures comprises a ferrous material.
 5. The systemof claim 3, wherein each of the plurality of pressurization structurescomprises a magnetized material.
 6. The system of claim 1, wherein eachof the plurality of pressurization structures has an annular shape. 7.The system of claim 1, wherein each of the actuators comprises amagnetic controller.
 8. The system of claim 7, wherein each the magneticcontroller comprises a magnet.
 9. The system of claim 8, wherein eachthe magnetic controller comprises an electromagnet.
 10. The system ofclaim 8, wherein each the magnetic controller is oriented and located soas to repel a corresponding pressurization structure toward a backsideof a semiconductor device structure assembled with the supportstructure.
 11. The system of claim 8, wherein each the magneticcontroller is oriented and located so as to attract a correspondingpressurization structure toward a backside of a semiconductor devicestructure assembled with the support structure.
 12. The system of claim1, wherein the actuators comprise a positive pressure source.
 13. Thesystem of claim 1, wherein the actuators comprise a negative pressuresource.
 14. The system of claim 13, wherein the pressurization componentfurther comprises at least one spring associated with each of theplurality of independently movable pressurization structures.
 15. Thesystem of claim 14, wherein the at least one spring biases acorresponding pressurization structure against the backside.
 16. Thesystem of claim 15, wherein the negative pressure source is configuredto withdraw the corresponding pressurization structure away from thebackside.
 17. The system of claim 1, wherein each actuator is configuredto bias a corresponding pressurization structure against a backside of asemiconductor device structure assembled with the support structure withvariable amounts of force.
 18. The system of claim 1, wherein thepolishing component comprises a mechanical polishing apparatus.
 19. Thesystem of claim 1, wherein the polishing component comprises achemical-mechanical polishing apparatus.
 20. The system of claim 1,wherein the polishing component includes assembled therewith a rotatablepolishing pad.
 21. The system of claim 1, wherein the polishingcomponent includes an element for rotating the semiconductor devicestructure in a plane thereof and relative to a polishing pad assembledwith the polishing component.